A method for preparing rice starch with high resistant starch content

Abstract

The present invention relates to the technical field of functional starch preparation, and a method for preparing rice starch with high resistant starch content of the present invention comprises three steps of rice starch extraction, preparation of a hydrophilic colloid-rice starch mixture, and wet heat treatment of the mixture. Compared with the prior art, the present invention has the following beneficial effects: the rice starch with high resistant starch content prepared by the method of the present invention is that a hydrophilic colloid is introduced into the rice starch, so that the rice starch and the hydrophilic colloid are wet-heat copolymerized; the hydrophilic colloid is combined with the rice starch by wet heat treatment, the content of resistant starch in the rice starch is increased, and the digestibility of the rice starch is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of functional starch preparation, and particularly relates to a method for preparing rice starch with high resistant starch content. Background Art

[0002] Obesity, diabetes and hyperlipidemia are all chronic metabolic diseases caused by multiple factors such as genetics and the environment. The three are closely related. Disorders in lipid metabolism can lead to obesity, and obesity is the biggest cause of diabetes. The probability of obese people suffering from diabetes is more than 4 times higher than that of normal people. At present, the main methods for regulating lipid metabolism in the body are moderate exercise, diet control and drug treatment. These methods are not easy to operate, have slow effects or produce side effects and adverse reactions. For example, long-term use of drugs can also produce toxicity and drug resistance.

[0003] In addition to the above three methods of controlling blood lipids, there is also a method of using edible modified starch to achieve the purpose of controlling blood lipids. However, the chemical modification method will produce a large amount of industrial wastewater during processing and production, polluting the environment. At the same time, the safety of chemically modified starch needs to be improved, and consumers' acceptance is poor.

[0004] In view of this, this patent is applied for. Summary of the invention

[0005] In order to overcome the shortcomings of the existing technology, this patent uses wet heat treatment of a hydrophilic colloid-rice starch mixture to prepare a hydrophilic colloid-rice starch copolymer, increases the resistant starch content through wet heat treatment, and uses locust bean gum as a hydrophilic colloid to solve the problems of chemically modified industrial wastewater and food safety.

[0006] The object of the present invention is to provide a method for preparing rice starch with high resistant starch content.

[0007] According to a specific embodiment of the present invention, a method for preparing rice starch with high resistant starch content comprises the following steps:

[0008] (1) Rice starch extraction:

[0009] The rice is soaked in water, wet-milled, dried in a blast oven, and then passed through a 100-mesh sieve to obtain rice flour; the rice flour is mixed with a 0.2% NaOH solution by weight in a ratio of 1:5, and placed on a shaker for reaction for 24 hours, during which the NaOH solution is replaced once, and centrifuged at room temperature, and the obtained precipitate is washed with water until the pH value of the upper layer liquid is neutral; the obtained starch wet block is dried and passed through a 100-mesh sieve, and the obtained powder is rice starch, which is stored in a desiccator for standby use;

[0010] (2) Preparation of hydrophilic colloid-rice starch complex:

[0011] 1 part by weight of the hydrophilic colloid is mixed by magnetic stirring in a 90° C. water bath to fully hydrate the colloid, and then taken out and cooled; the rice starch obtained in step (1) is added to the colloid solution, stirred at room temperature for 30 minutes, and then dried in a 45° C. oven to a water content of less than 10%, and then crushed through a 100-mesh sieve to obtain a hydrophilic colloid-rice starch complex;

[0012] (3) Wet heat treatment:

[0013] The hydrophilic colloid-rice starch complex obtained in step (2) is subjected to moisture adjustment and moisture balance for 24 hours, and the complex is transferred into a polytetrafluoroethylene tube, sealed in a reaction kettle for reaction, naturally cooled to room temperature, stored at 4° C. for 24 hours, dried at 45° C., crushed, sieved through a 100-mesh sieve, sealed and dried for storage, to obtain rice starch with a high resistant starch content.

[0014] According to the preparation method of a specific embodiment of the present invention, in the step (2), the amount of rice starch added is 10-50 parts by weight.

[0015] According to the preparation method of a specific embodiment of the present invention, the amount of rice starch added is 30 parts by weight.

[0016] According to the preparation method of a specific embodiment of the present invention, in the step (3), the water content of the hydrophilic colloid-rice starch complex during the reaction is 20%-35%.

[0017] According to the preparation method of a specific embodiment of the present invention, the moisture content is 25%.

[0018] According to the preparation method of a specific embodiment of the present invention, in the step (3), the reaction temperature is 110°C-130°C.

[0019] According to the preparation method of a specific embodiment of the present invention, the reaction temperature is 130°C.

[0020] According to the preparation method of a specific embodiment of the present invention, in the step (3), the wet heat reaction time is 1-4 hours.

[0021] According to the preparation method of the specific embodiment of the present invention, in the step (3), the wet heat reaction time is 2h

[0022] According to the preparation method of a specific embodiment of the present invention, in the step (2), the hydrophilic colloid is locust bean gum.

[0023] The locust bean gum selected by the present invention is also known as locust bean gum, bean gum, and carob gum. It is a galactomannan processed from the seed endosperm part of the locust plant carob. Locust bean gum is connected by β-D-(1-4) glycosidic bonds, with D-mannose as the main chain, and an α-D-pyranose galactose is connected to the 1 and 6 positions of certain D-mannose groups, and the ratio of galactose to mannose is 1:4. Locust bean gum is mainly used as a thickener, emulsifier, and stabilizer in the food industry. As a pure natural substance, locust bean gum has good safety when used in food.

[0024] At the same time, for other peptides, such as collagen peptides, the present invention has the following advantages:

[0025] 1. Compared with collagen peptides, locust bean gum has a lower cost price;

[0026] 2. The proportion of locust bean gum added by this method is small, only 3.33% of the total amount, while collagen peptide products need to add 41.18%;

[0027] 3. Collagen peptides add a lot of peptide substances to starch products and cannot be widely used in all food fields. Locust bean gum itself, as a polysaccharide, will not increase the content of non-polysaccharide substances when mixed with rice starch;

[0028] 4. The final proportion of resistant starch obtained is higher than that of collagen peptide (the resistant starch content of this method is 66.04%, and the collagen peptide method increases it by 23.98%).

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The rice starch with high resistant starch content prepared by the method of the present invention comprises the following steps: a hydrophilic colloid is introduced into the rice starch so that the rice starch and the hydrophilic colloid are subjected to wet-heat copolymerization; the hydrophilic colloid is combined with the rice starch by wet-heat treatment, the content of resistant starch in the rice starch is increased, and the digestibility of the rice starch is reduced.

[0031] Instruction Manual

[0032] Figure 1 The effect of heat-moisture treatment temperature on the content of resistant starch in rice;

[0033] Figure 2 The effect of heat treatment time on the resistant starch content of rice;

[0034] Figure 3 The effect of different moisture contents on the resistant starch content of rice;

[0035] Figure 4 The effect of different types of colloids on the resistant starch content of rice. DETAILED DESCRIPTION

[0036] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0037] The locust bean gum used in the present invention was purchased from Shandong Pingju Biotechnology Co., Ltd., and other raw materials can be obtained through common commercial channels and are not specifically limited here.

[0038] Example 1

[0039] The rice starch with high resistant starch content and the preparation method thereof of the present invention comprise the following steps:

[0040] (1) Rice starch extraction:

[0041] Rice is soaked in water and wet-milled. After drying in a blast oven, it is sieved through a 100-mesh sieve to obtain rice flour. Rice flour is mixed with 0.2% NaOH solution in a ratio of 1:5 and placed on a shaker for reaction, during which the NaOH solution is changed once; centrifuged at room temperature, the supernatant is discarded, and the precipitate is washed with water several times until the pH value of the upper layer is neutral; the starch wet block is dried and sieved through a 100-mesh sieve, and the resulting powder is rice starch, which is stored in a dryer for later use;

[0042] (2) Preparation of hydrophilic colloid-rice starch mixture:

[0043] 1 part by weight of locust bean gum was mixed with magnetic stirring in a 90°C water bath to fully hydrate the gum, and then taken out and cooled. 30 parts by weight of rice starch (dry basis) was added to the gum solution, and stirred at room temperature for 30 minutes, dried in a 45°C oven, crushed, and passed through a 100-mesh sieve to obtain a hydrophilic colloid-rice starch complex;

[0044] (3) Hygrothermal treatment of mixture:

[0045] Take the hydrophilic colloid-rice starch complex prepared in step (2) and adjust the water content to 25%, and balance the water content for 24 hours. Transfer the complex to a polytetrafluoroethylene tube, seal it in a reaction kettle, and perform wet heat reaction at 130° C. for 2 hours. Cool it naturally to room temperature and store it at 4° C. for 24 hours; dry it at 45° C., crush it, pass it through a 100-mesh sieve, and seal it for drying and storage.

[0046] Finally, the resistant starch content of rice starch was 66.04%. The resistant starch determination method, the specific operation steps are as follows: 500 mg of sample and 5 mL of 0.5 mol / L NaAc buffer (pH 5.2) were added to a 50 mL centrifuge tube and mixed thoroughly. Boil in a water bath for 20 minutes, then transfer to a 37 ° C water bath shaker and shake at a speed of 170 r / min. 50 mg of pepsin and 50 mg of guar gum were added to 10 mL of 0.05 mol / L HCl, respectively, and added to the sample centrifuge tube for 30 minutes after stirring. Then, 7 glass beads (diameter: 3-4 mm) and 5 mL of NaAc buffer (0.5 mol / L, pH 5.2) were added to the tube and shaken for 30 minutes. Then, 10 mL of mixed enzyme (containing pancreatic extract and amyloglucosidase) was added. At a specific time point, an aliquot (0.5 mL) was taken from the sample tube and mixed with 4 mL of 80% (v / v) ethanol solution to inactivate the enzyme. Centrifuge at 10000r / min for 5min, take the supernatant, and use the glucose oxidase kit (GOPOD) at 520nm to measure the released glucose content with an enzyme reader. The total starch mass (TS) is determined by boiling the sample after the digestion reaction for 30min, ice bathing for 10min, adding 10mL 7mol / L KOH solution, and placing it in a 4℃ refrigerator for 30min. Take 0.5mL of the sample and add 5mL 0.5mol / L acetic acid solution to mix, then add 50μL amyloglucosidase, shake in a 70℃ water bath for 30min, take an aliquot (50μL) from the sample tube, and mix with 950μL anhydrous ethanol to kill the enzyme. Centrifuge at 10000r / min for 5min, take the supernatant, and use the glucose oxidase kit (GOPOD) at 520nm to measure the glucose content in the solution with an enzyme reader to calculate TS.

[0047] Among them, the different digestion components are calculated as follows:

[0048] RDS=G20*0.9 (2-9)

[0049] SDS=(G120-G20)*0.9

[0050] RS=(TS-G120)*0.9

[0051] Where: G20 is the glucose content in the supernatant after 20 minutes of digestion, G120 is the glucose content in the supernatant after 120 minutes of digestion, TS is the total starch mass, and 0.9 is the glucose conversion coefficient.

[0052] Example 2

[0053] The difference between this embodiment and embodiment 1 is that:

[0054] In step (2), 1 part by weight of locust bean gum is mixed with magnetic stirring in a 90° C. water bath to fully hydrate the gum, and then taken out and cooled. 50 parts by weight of rice starch (dry basis) is added to the gum solution, stirred at room temperature for 30 minutes, placed in a 45° C. oven to dry, crushed, and passed through a 100-mesh sieve.

[0055] The resistant starch content of the rice starch finally obtained was 23.35%.

[0056] Example 3

[0057] The difference between this embodiment and embodiment 1 is that:

[0058] In step (3), the water content of the hydrophilic colloid-rice starch complex is adjusted to 20%, and the water content is balanced for 24 hours. The complex is transferred into a polytetrafluoroethylene tube, sealed in a reaction kettle, and subjected to a wet heat reaction at 130° C. for 2 hours. After naturally cooling to room temperature, it is stored at 4° C. for 24 hours; dried at 45° C., crushed, passed through a 100-mesh sieve, and sealed for dry storage.

[0059] The resistant starch content of the rice starch finally obtained was 59.72%.

[0060] Example 4

[0061] The difference between this embodiment and embodiment 1 is that:

[0062] In step (3), the water content of the hydrophilic colloid-rice starch complex is adjusted to 35%, and the water content is balanced for 24 hours. The complex is transferred into a polytetrafluoroethylene tube, sealed in a reaction kettle, and subjected to a wet heat reaction at 110° C. for 1 hour. After naturally cooling to room temperature, it is stored at 4° C. for 24 hours; dried at 45° C., crushed, passed through a 100-mesh sieve, and sealed for drying and storage.

[0063] The final resistant starch content of the rice starch was 42.23%.

[0064] Parameter optimization experiment:

[0065] Experimental method: Weigh a certain amount of rice starch and adjust the moisture to 20%, 25%, 30%, and 35%, place the rice starch with adjusted moisture in the inner core of the reactor, and put it in a 4°C refrigerator for 24 hours to balance the moisture, then take it out, put it in a reactor and put it in 100°C, 110°C, 120°C, and 130°C ovens for 1h, 2h, 3h, and 4h, respectively, put it in a 4°C refrigerator again for 24h, take it out after drying in a 45°C oven for 24h, grind it and pass it through a 100-mesh sieve.

[0066] Experimental conclusion:

[0067] Depend on Figure 1As known, when the moisture content of rice starch is adjusted to 25%, the reaction time is 2h, and the reaction temperature is 100℃, 110℃, 120℃, and 130℃, the resistant starch content gradually increases with increasing temperature, and the maximum value is 14.00% at 130℃.

[0068] Depend on Figure 2 As known, when the reaction time is 2h and the reaction temperature is 130°C, the moisture is adjusted to 20%, 25%, 30%, and 35% respectively. The resistant starch content first increases and then decreases with the moisture content, and the highest value is 14.00% at 25%.

[0069] Depend on Figure 3 As known, when the moisture content of rice starch was adjusted to 25%, the reaction temperature was 130°C, and the reaction times were 1h, 2h, 3h, and 4h, respectively, the resistant starch content first increased and then decreased with time, with the highest value of 14.00% at 2h.

[0070] Depend on Figure 4 As known, when the weight ratio of hydrophilic colloid to rice starch is 1:10, the moisture content of rice starch is adjusted to 25%, the reaction temperature is 130°C, and the reaction time is 2h, the highest value of resistant starch with different hydrophilic colloids is 53.28% when locust bean gum is added.

[0071] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing rice starch with high resistant starch content, the method comprising the following steps: (1) Rice starch extraction: The rice is soaked in water, wet-milled, dried in a blast oven, and then passed through a 100-mesh sieve to obtain rice flour; the rice flour is mixed with a 0.2% NaOH solution by weight in a ratio of 1:5, and placed on a shaker for reaction for 24 hours, during which the NaOH solution is replaced once, and centrifuged at room temperature, and the obtained precipitate is washed with water until the pH value of the upper layer liquid is neutral; the obtained starch wet block is dried and passed through a 100-mesh sieve, and the obtained powder is rice starch, which is stored in a desiccator for standby use; (2) Preparation of hydrophilic colloid-rice starch complex: 1 part by weight of a hydrophilic colloid is mixed by magnetic stirring in a 90° C. water bath to fully hydrate the colloid, and then taken out and cooled; the rice starch obtained in step (1) is added to the colloid solution, stirred at room temperature for 30 minutes, and then dried in a 45° C. oven to a water content of less than 10%, and then crushed through a 100-mesh sieve to obtain a hydrophilic colloid-rice starch complex; the hydrophilic colloid is locust bean gum; (3) Wet heat treatment: The hydrophilic colloid-rice starch complex obtained in step (2) is subjected to moisture adjustment and moisture balance for 24 hours, and the complex is transferred into a polytetrafluoroethylene tube and sealed in a reaction kettle for reaction at a reaction temperature of 130° C. and a reaction time of 2 hours, and then naturally cooled to room temperature and stored at 4° C. for 24 hours, dried at 45° C., crushed, sieved through a 100-mesh sieve, sealed and dried for storage, to obtain rice starch with a high resistant starch content; during the above reaction, the moisture content of the hydrophilic colloid-rice starch complex is 20%-35%.

2. The method for preparing rice starch with high resistant starch content according to claim 1, characterized in that: In the step (2), the amount of rice starch added is 10-50 parts by weight.

3. The method for preparing rice starch with high resistant starch content according to claim 2, characterized in that: The added amount of the rice starch is 30 parts by weight.

4. The method for preparing rice starch with high resistant starch content according to claim 1, characterized in that: The moisture content is 25%.

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